We hypothesize that strengthening muscles may be an alternative for improving gait and function in children with cerebral palsy. Our long-term objective is to develop an improved strengthening therapy compared to today's approaches. Our proposed therapy is based on the use of a prototype Rutgers Ankle robot integrated with game-like virtual reality (VR) simulations. SPECIFIC AIMS The first aim is to develop the Rutgers Ankle CP for use in strengthening the ankles of children with CP. The second aim is to determine if a 12-week intensive ankle dorsi/plantarflexors strength-training program on the Rutgers Ankle CP will improve ankle strength, gait, function, and quality of life of children with CP. METHODS 1) we will construct the Rutgers Ankle CP system and modify the robot servo control to allow active assistance/passive resistance to ankle motion;2) we will expand virtual rehabilitation software for children with CP training on the Rutgers Ankle CP. A new intelligent agent software will correlate task exertion requirements with patient past performance in order to determine the robot behavior (from 100% assistance to 100% resistance);3) we will develop a web-accessible database module for reporting and data analysis. Data from the Rutgers Ankle CP will be sampled transparently in real time at the clinical site. Subsequently the data will be forwarded over the Internet to an existing database server at Rutgers University. The existing web-based clinical database and graphing environment will be enhanced to include conventional CP clinical evaluation measures, computerized variables from the VR exercises, and subjective evaluation questionnaires;4) Six subjects with spastic diplegia CP will participate in a 12-week strength-training program of the ankle dorsi/plantarflexors on the Rutgers Ankle CP. Subjects will be evaluated for ankle strength, spasticity, gait analysis, GMFM, and Peds QL prior to the intervention, at the end of the 12-week intervention, and after an additional 12 weeks. We hypothesize that the subjects will improve in strength, gait, function, and quality of life from training on the robot, and will maintain the gains for at least 12 weeks. NIH RELEVANCE This project will develop a device for ankle strength training in CP. The strength training can be used to improve gait and function. PUBLIC HEALTH RELEVANCE A simple strength training program that improves gait and function will reduce health care costs by eliminating or delaying more expensive procedures.